Explanation:
To the eye,
this cosmic composition
nicely balances the
Bubble Nebula at the upper right with open star cluster M52.
The pair would be lopsided on other scales, though.
Embedded in a complex of
interstellar dust
and gas and blown by the winds from a single, massive
O-type star, the
Bubble Nebula (aka NGC 7635) is a
mere 10 light-years wide.
On the other hand,
M52 is a rich open
cluster of around a thousand stars.
The cluster is about 25 light-years across.
Seen toward the northern boundary
of Cassiopeia, distance estimates
for the Bubble Nebula and associated cloud complex are around
11,000 light-years, while
star cluster M52
lies nearly 5,000 light-years away.